Gatlin 'hungry' for Rio success

US sprinter Justin Gatlin said he was "hungry" for success as he prepares to take on Usain Bolt for what would be a highly controversial second Olympic crown.

Gatlin has twice served doping bans in his career, meaning a 100m or 200m win against the popular Bolt would be polarising -- especially after Russia's athletics team was suspended over a drugs scandal.Gatlin, 34, has set the two fastest times this year and he is a real threat to two-time defending champion Bolt, whose build-up has been troubled by a hamstring injury.

He said he was taking a simple approach to what will be his third Olympics, after he won the 100m in 2004, missed 2008 with a drugs ban and returned to take bronze in 2012. "I'm just going to go out and do what I need to do," he told reporters at the US track and field team's training base near Copacabana.

"This Olympics is going to be special. I know everyone's going to bring their A-game so I've got to make sure I'm ready.

" When asked how he was feeling, Gatlin told reporters: "Hungry." "This is my third Olympics so I'm bringing the fun, care-free Justin Gatlin from 2004 and the honoured-to-be-here Justin Gatlin from 2012, kind of mixed together," he said.

"When I go out there I'm just going to celebrate and have a great time." Gatlin set personal bests over both 100m and 200m last year, raising eyebrows after Norwegian researchers found in 2014 that the effects of performance-enhancing drugs could last for decades.

He looked favourite to beat Bolt at last year's world championships over 100m, but was ultimately undone in both sprints by commanding performances from the Jamaican. It was perhaps just as well after Britain's Sebastian Coe, now head of athletics body the IAAF, said the prospect of giving Gatlin a world championships gold medal made him "queasy". But Gatlin said he was inspired to continue competing by fans urging him on through social media.

"The fans, just giving well-wishes through social media, just hoping I come out here and do what I need to do as an American and as an athlete," he said,when asked how he found the drive to stay at the top of his sport. "That's what gives me the drive to keep going forward."

Gatlin is not America's only drug-tainted sprinter. LaShawn Merritt  who served a 21-month ban for testing positive for a banned steroid in 2010  could threaten Bolt over 200m. And Tyson Gay returns as a member of the 4x100m relay squad after completing a one-year suspension for testing positive for a banned steroid.